This invention relates to bicomponent textile filaments of nylon and polyester, the components of which adhere to each other during fiber processing, but may be split into component parts after fabrication into fabric. This invention also relates to a process of producing such bicomponent textile filaments.
Bicomponent textile filaments of nylon and polyester are known in the art, and are described in Tanner U.S. Pat. No. 3,117,906. Stanley U.S. Pat. No. 4,118,534 also discloses and claims such filaments, and teaches that the tendency of such filaments to presplit (i.e. split before the filaments are made into fabric) can be reduced by including in the nylon component aminopropylmorpholine and bis-hexamethylenetriamine. Nishida U.S. Pat. No. 3,917,784 discloses bicomponent nylon/polyester filaments, and teaches that the adhesion between the components can be improved by use of a particular type of spinning oil.
The present invention is also directed at a solution to the problem of pre-splitting of the bicomponent fiber into its components. Pre-splitting is a problem that can arise during fiber windup or in weaving or knitting whenever external stresses exceed component adhesion. Pre-splitting of bicomponent filaments is believed to have been one of the major reasons that nylon/polyester bicomponent fibers have not become of greater commercial significance.
It has now been found that the problem of pre-splitting can be largely overcome by employing a polyester component in the fiber that is substantially free of any ingredient that, under the conditions of spinning, is capable of reacting with any ingredient in the nylon component and precipitating as a deposit on the inside wall of the spinneret capillary. Some of the most common ingredients in polyester resins that are capable of reacting with nylon to form a precipitate on the inside wall of the spinneret capillary are antimony compounds; antimony compounds are an ingredient in most commercial catalysts used to produce textile polyester resins. When a polyester containing such an ingredient is spun through a spinneret aperture with nylon, the precipitate forms and deposits along the junction line of the two polymers, and the spinneret aperture gets smaller at the junction line leading to a shorter junction line and thus a weaker junction line and one more likely to pre-split. When a polyester containing an antimony compound is employed in the production of bicomponent fibers with nylon, the precipitate which forms contains a high concentration of antimony compounds. This change in cross sectional shape of the filament gives rise to a second problem, namely a nonuniformity or streak problem in the final fabric, for when a fabricator produces a fabric, several different bobbins of yarn are employed, and fiber cross sectional differences between two different bobbins are often optically apparent in the fabric. The product of this invention is a nylon/polyester bicomponent filament which is substantially free from antimony. The product of this invention is a nylon/polyester bicomponent filament that has substantially the same cross sectional dimensions throughout its length.
It is more economically attractive to use a polyester that is substantially free from any ingredient that is capable of reacting with nylon and precipitating as a deposit, that it is to stop the spinning and remove the deposit.